I've installed zorin core as dual boot on my PC though it still using 37%+ memory even during idle what could be using such memory, the only app open on the foreground is the "system monitor"
Version of Zorin?
15.3 or 16?
Zorin OS Core 15.3
How much RAM do you have?
In addition to addressing zabadabadoo's question and testing your RAM:
If this is a fresh install, I would just wipe and reload.
What you are describing sounds like a memory leak.
process such as evolution-*, ibus and pulseaudio are using like 20%+ of the resources,
I have a 4GB physical memory though
I've been searching ways to solve this memory leak for weeks, some solutions breaks the system chain so I decided to use another Linux distro, I'll still keep open this issues for any future solutions because it's also an issue in Ubuntu which I'm hoping to migrate into